Coupling between magnetic order and charge transport in the two-dimensional magnetic semiconductor CrSBr

Semiconductors, featuring tunable electrical transport, and magnets, featuring tunable spin configurations, form the basis of nearly all information technologies. A long-standing challenge has been to realize materials that integrate these two distinct properties. Two-dimensional (2D) materials offer a new platform to realize this concept, but the recently discovered 2D magnetic semiconductors are found to be electrically insulating in their magnetic phase. Here we demonstrate tunable electron transport within the magnetic phase of the 2D semiconductor CrSBr and reveal strong coupling between its magnetic order and charge transport. This provides a previously unrealized opportunity to characterize the layer-dependent magnetic order of CrSBr down to the monolayer via magnetotransport. Exploiting the sensitivity of magnetoresistance to magnetic order, we uncover a second magnetic transition ascribed to the ferromagnetic ordering of magnetic defects. The magnetoresistance of this hidden magnetic phase can be dynamically and reversibly tuned by varying the carrier concentration using an electrostatic gate, providing a new mechanism for controlling charge transport in 2D magnets.